In many ways it has made knowledge accessible to all people that have access to it. This means that many people that never had access to the best information now do. Intelligence is not accurately measurable due to it being largely a matter of opinion and that by definition means it is measured from a defined point of view that of the tester, or the test developer.
When testing someone more intelligent than them the results will not be accurate. The wide spread nature of the web has given all with access the possibility to read better articles, learn languages and music skills. We know that aptitude in all of these in general will increase intelligence. The issue is that much of what is on the internet is not true so a reasonable degree of intelligence is required to avoid the pitfalls.
On balance I believe it is an opportunity opener, which like books an tutors care has to be taken in deciding which parts you are going to trust. This seems to be the crux of the problems Google has in deciding which sites to promote. It is difficult for humans and almost impossible fo robots to get right.